Female Reproductive System 3: The menstrual cycle and menopause

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What are the stages of the menstrual cycle?

Proliferative Phase:

Oestrogen is produced by the follicle, promoting proliferation of the endometrium epithelial cells. Replacement of the functional zone of the uterus begins.

Secretory Phase:

After ovulation, the corpus luteum secretes progesterone. The uterine glands increase their secretion and the endometrial lining is thickened. The secretory phase lasts 14 days.

Menses:

Menses occurs when it is a non-pregnancy case. There is a hormone level drop where the functional zone of the uterus is shed (stratum functionalis is sloughed off). The layer is shed because the endometrial blood vessels become constricted and there is decreased oxygen and nutrients supplied to the lining. The cells disintegrate and blood escapes from the damage capillaries, and with the cellular debris this makes up the menstrual fluid. A new ovarian cycle begins during menses.

Combined Oral Contraceptive Pill

The combined oral contraceptive pill gives minute doses of oestrogens and progesterone. It slows the hypothalamic-pituitary actions:
  • Through negative feedback, it decreases GnRH
  • It inhibits follicular development and prevents ovulation
  • It increases cervical mucous to inhibit sperm from meeting ova

What is menopause?

Menopause is the cessation of ovulation and menstruation. It occurs after approximately 450 ovarian cycles (45-55 years). It involves fluctuating and decreasing levels of hormones:
  • Decreases oestrogen and progesterone concentration
  • Decreased responsiveness of ovaries to FSH and LH
  • Increased concentration of GnRH, which increases FSH and LH levels
In menopause, the follicles fail to mature. It presents with the following signs and symptoms:
  • Regression fo secondary sexual characteristics: ↓ breast size, ↓ reproductive organ size
  • Anxiety and depression can occur
  • Bone density is reduced (↑ risk of osteoporosis)
  • "Hot flush" symptoms
  • HRT (treatment to reduce symptoms of menopause)

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